The turn of the century witnessed an influx of cell culture in experimentation. However, few of the advancements made were as pivotal as the work conducted by Ross Granville Harrison at Johns Hopkins University in 1907. To this point, in vitro work had become quite good at observing organic tissue microscopically, however, attempts to manipulate cells had proven difficult. Studying the development of nerve fibres, Harrison was able to successfully culture, maintain, and grow nerve cells outside of the body – detailing the process by which nerve endings originate. His technique, the ‘hanging drop’, combined frog embryonic nerve fragments and frog lymphoid tissue by drops, which were then covered by a sterile coverslip. When the lymph clotted, the apparatus would be inverted over a glass depression slide maintaining the organic materials and allowing them to be observed for a period of time. This proved to be a vital breakthrough in cell culture that confirmed or rejected many existing theories and provided the means to develop new ones to expand the field.
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